5J-1 Simultaneous Imaging and Therapeutic Ultrasound (Invited)

High intensity focused ultrasound has been shown to be very effective for thermally ablating localised tumours through extracorporeal or endocavitary routes. More recently, miniature interstitial ultrasound probes have been investigated for the treatment of deep-seated tumours. All treatments must be performed under imaging guidance in order to bring the probe focus precisely on the targeted site and to monitor the treatment on-line. Imaging objectives and constraints may vary depending on the targeted organs, access routes, and treatment process. MRI provides high contrast images and is presently recognized as the gold standard for thermal mapping. MRI compatible high intensity ultrasound transducers have been designed for this purpose. Conventional B mode imaging is efficient at visualising scattering gas bodies. Many other ultrasound techniques have been tested and are likely to be further developed in order to make use of the large potential of ultrasound for targeting and monitoring the treatments. More recently it has been shown that dual mode transducers can be used for both imaging and therapeutic objectives. This again opens new possibilities for extracorporeal, endo-cavitary and interstitial applications. In all the cases, the therapeutic transducer has to be designed with the chosen imaging modality in mind